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Pinch off hose for towing in water
- Thread starter sandals99
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![IMG_1827[1].jpg](https://www.seadooforum.com/data/attachments/24/24363-357258ab69f909dd8b1f94f200a21b2a.jpg?hash=NXJYq2n5Cd "IMG_1827[1].jpg")
Joshualmarley
New Member
Subscribed. I have the same question
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
xintersecty
New Member
Negative Ghost rider, you have the wrong hose. Love that line. You need to pinch off the line before the header. If you look in the picture below, item no 10.
Compliments on taking a picture and asking. So find your pump and pinch off the bigger hose. You want to stop the water before it get's to the header. The hose you circle would have been past the the exhaust header.
Compliments on taking a picture and asking. So find your pump and pinch off the bigger hose. You want to stop the water before it get's to the header. The hose you circle would have been past the the exhaust header.
Sportster-2001-951C-Stock
Well-Known Member
The idea is to avoid flooding the exhaust system with water that can back up into the exhaust ports of the engine and fill the cylinders with water. Pinching that hose should accomplish the goal b/c it keeps water from exiting the exhaust manifold cooling jacket and flowing into the exhaust system.
Optional, maybe a good idea:
After towing and back on the trailer, remove the spark plugs, ground the plug wires, open the throttle completely and crank the engine while watching for water coming from the cylinder spark plug holes. If no water, you succeeded in avoiding flooding the engine with water.
For confirmation, your owners manual should also provide instructions for which hoses to pinch while towing in water, and it's probably in the factory service/maintenance manual as well.
Optional, maybe a good idea:
After towing and back on the trailer, remove the spark plugs, ground the plug wires, open the throttle completely and crank the engine while watching for water coming from the cylinder spark plug holes. If no water, you succeeded in avoiding flooding the engine with water.
For confirmation, your owners manual should also provide instructions for which hoses to pinch while towing in water, and it's probably in the factory service/maintenance manual as well.
Sportster-2001-951C-Stock
Well-Known Member
I believe you are correct RCguy, some people don't want to take a chance and that's okay too.
Pinching either hose referenced above will accomplish the goal of keeping the exhaust from filling with water and flooding the cylinders.
pete63
Active Member
i have put a on/off valve on the inlet hose. no more searching for a clamp.
for me it doesnt matter what speed im getting towed at, you can never be sure (tidal flow, river current speed etc). i rather do that than flushing water out of the engine!!!
http://www.seadooforum.com/showthre...55-s-questions&p=434930&viewfull=1#post434930
for me it doesnt matter what speed im getting towed at, you can never be sure (tidal flow, river current speed etc). i rather do that than flushing water out of the engine!!!
http://www.seadooforum.com/showthre...55-s-questions&p=434930&viewfull=1#post434930
sandals99
New Member
Thanks everyone for all the replies. I'll take a look when we get back home, just got into Seattle to watch the 4th of July celebrations. Happy 4th of July to our neighbours down south!
Sportster2001, would it be ok to pinch off where I noted it in the picture? It looked very similar to the spot the Manual showed.
Xintersecty thanks for the diagram, I'll try to locate that on the boat
Sportster2001, would it be ok to pinch off where I noted it in the picture? It looked very similar to the spot the Manual showed.
Xintersecty thanks for the diagram, I'll try to locate that on the boat
Sportster-2001-951C-Stock
Well-Known Member
Yes, pinching either of the two hoses mentioned will accomplish the goal of stopping water flow through the manifold log into the exhaust. Either pinching the water supply to the exhaust manifold log or from the exhaust manifold log will keep water from filling the exhaust and backing up into the cylinders.
I suggest though if you want to, verify the engine wasn't flooded by removing the spark plugs and cranking once back on the trailer, that doesn't take long to accomplish and it's not a bad idea IMO if the boat sits for a week or more in the repair que full of water that could be an issue to avoid.. The ounce of prevention clause of Murphy's law.
I suggest though if you want to, verify the engine wasn't flooded by removing the spark plugs and cranking once back on the trailer, that doesn't take long to accomplish and it's not a bad idea IMO if the boat sits for a week or more in the repair que full of water that could be an issue to avoid.. The ounce of prevention clause of Murphy's law.
Many instal the valve as it is easy in the event you do need to two the ski.
The reason you need to pinch the hose (or use a valve) is, water will be forced into the exhaust through the pump (impeller) area. It fills the exhaust up and then goes to the top of the engine and sits there. The first tiem you crank you engine you will suck that standing water into the cylinders..
The reason you need to pinch the hose (or use a valve) is, water will be forced into the exhaust through the pump (impeller) area. It fills the exhaust up and then goes to the top of the engine and sits there. The first tiem you crank you engine you will suck that standing water into the cylinders..
Let me take a shot at explaining this:
The reason water gets sucked into the engine is because there is no "pump" that circulates water to cool the exhaust (and supercharger, if you have it). There are holes in the venturi that bleed water off when the impeller is pushing water through the jet pump. That force of water through the jet pump that propels the boat is also the pressure that forces some of that water up to the exhaust to cool it. When the engine is running, the exhaust gasses force that cooling water back out the exhaust port after it has completed the cooling loop.
When the engine is not running and the boat is sitting still, there is no pressure on the venturi to force water into the exhaust cooling loop - so, no problem with water entering the block. When you are getting towed, there is some water pressure (depending on speed) on the venturi, causing water to flow into the exhaust cooling loop. Once the loop fills up, it spills over into the exhaust. Once the exhaust fills up (remember, there is no exhaust gas pressure on the exhaust system to force water out of the exhaust outlet), water flows up to the head of the engine and sits there. When you crank the engine and the valves open, water falls into the cylinders and you get hydrolock.
This is why you can tow the boat at a low speed without a problem, but if you exceed the threshold where the venturi comes under pressure, you WILL fill the engine with water.
Clamping or valving off the venturi hose to the manifold will allow you to tow the boat at a faster speed and not fill the engine because the water under pressure in the venturi has nowhere to go.
The reason water gets sucked into the engine is because there is no "pump" that circulates water to cool the exhaust (and supercharger, if you have it). There are holes in the venturi that bleed water off when the impeller is pushing water through the jet pump. That force of water through the jet pump that propels the boat is also the pressure that forces some of that water up to the exhaust to cool it. When the engine is running, the exhaust gasses force that cooling water back out the exhaust port after it has completed the cooling loop.
When the engine is not running and the boat is sitting still, there is no pressure on the venturi to force water into the exhaust cooling loop - so, no problem with water entering the block. When you are getting towed, there is some water pressure (depending on speed) on the venturi, causing water to flow into the exhaust cooling loop. Once the loop fills up, it spills over into the exhaust. Once the exhaust fills up (remember, there is no exhaust gas pressure on the exhaust system to force water out of the exhaust outlet), water flows up to the head of the engine and sits there. When you crank the engine and the valves open, water falls into the cylinders and you get hydrolock.
This is why you can tow the boat at a low speed without a problem, but if you exceed the threshold where the venturi comes under pressure, you WILL fill the engine with water.
Clamping or valving off the venturi hose to the manifold will allow you to tow the boat at a faster speed and not fill the engine because the water under pressure in the venturi has nowhere to go.
Sportster-2001-951C-Stock
Well-Known Member
Water is injected into the exhaust system while the engine is running to keep the exhaust system cool, the source is the jet pump. The exhaust system cannot flood with water due to the continuous expansion of combustion gasses pushes the water out with the exhaust, so only small amounts of water are inside the exhaust while running.
If the boat is towed fast enough with the engine not running, there will be water flowing through the exhaust cooling system. If either the hose dumping water into the exhaust water box or the supply hose isn't pinched, the exhaust water box will completely fill with water and water will back up into the exhaust ports of the combustion chambers.
The jet pump provides the cooling water normally while the engine is running but it can also provide some water while the boat is moving through the water b/c the jet pump has the basic shape of a large funnel and there will be water pressure inside while the boat is moving through the water.
The boat has to be moving at a fairly high speed but you might not want to take a risk. Some tow guys like to go fast, maybe they're not on the clock? Not sure how fast your towboat will insist on running but if fast enough, your engine will take a gulp of water if it's not running thus pushing the water out of the exhaust system by force of the exhaust gasses.
If the boat is towed fast enough with the engine not running, there will be water flowing through the exhaust cooling system. If either the hose dumping water into the exhaust water box or the supply hose isn't pinched, the exhaust water box will completely fill with water and water will back up into the exhaust ports of the combustion chambers.
The jet pump provides the cooling water normally while the engine is running but it can also provide some water while the boat is moving through the water b/c the jet pump has the basic shape of a large funnel and there will be water pressure inside while the boat is moving through the water.
The boat has to be moving at a fairly high speed but you might not want to take a risk. Some tow guys like to go fast, maybe they're not on the clock? Not sure how fast your towboat will insist on running but if fast enough, your engine will take a gulp of water if it's not running thus pushing the water out of the exhaust system by force of the exhaust gasses.
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